The big question at the end of ‘Legend’ is just how much an impact can a single actor have on the overall result of a movie. For the most part, Brian Helgeland’s take on the notorious London gangsters the Kray brothers is fairly average. However, at the center of it is a pretty damn remarkable pair of performances as the twin criminals from Tom Hardy. The film is worth seeing for his amazing work alone, even if most of what goes on around Hardy is fairly forgettable.

For those unfamiliar with the truth or the legends, the flamboyant Kray brothers ruled over the London underworld during the 1960s, eventually even earning a shot at becoming legitimate businessmen (well, as much as possible for a pair of hardened and hardcore criminals). As this film tells it, Reggie (Hardy) was the most stable of the two. Sure, he was excellent at cracking skulls, but he also had ambitions toward a legitimate life and the brains to pull it off. On the other hand, Ronnie (Hardy again) was a straight-up nutter who enjoyed the violence as much as the power.

That morality split between the two gangsters might be dramatically convenient, but the main reason the film clings to that perspective is also the movie’s biggest downfall. The tale is narrated by Reggie’s wife (Emily Browning), and even though she’s technically at the center of the movie, Helgeland can never quite figure out what to do with her.

Browning’s purpose in the story is to humanize Reggie and help the audience see him through empathetic eyes. That makes sense dramatically as a means of giving the movie a digestable good brother/bad brother dynamic. However, the trouble is that even though Browning is a talented actress, she never has much of a character to play. She’s always to the side of the main crime story even though it’s told from her perspective, and her character is never defined beyond being a vision of good. It’s rather frustrating, even irritating.

Thankfully, even though that character takes up so much of the hefty 131-minute running time, she’s hardly a movie killer. After all, the Krays are fascinating figures and Tom Hardy just might be the finest actor of his generation. He plays both roles so well and so distinctly that you’ll often forget you’re watching a single actor. As Reggie, he’s a charmingly evil figure, a thug masquerading as a rogue that Hardy plays so well it’s easy to fall for the movie’s trap and think he’s secretly a hero. As Ronnie, Hardy dives into full-on cartoony psychopath territory. He garbles his speech to the point that it almost sounds like his tongue is three sizes too big. Even in the quietest moments, he seems seconds away from a murderous outburst. Unlike Hardy’s more grounded Reggie, his turn as Ronnie is highly theatrical. It would almost feel too much were it not for the tone of the movie.

Writer/director Helgeland is of course no stranger to crime flicks. He won an Oscar for co-writing ‘L.A. Confidential’ after all, though the tone of ‘Legend’ is closer to his darkly comedic ‘Payback’. This movie might be based on real people and has a sense of shock and tragedy, but a darkly comedic tone hangs over most of the running time. It’s probably too much to describe the movie as a sick comedy, but in its best moments that’s what Helgeland strives for and Hardly cannily delivers, along with a string of recognizable supporting faces like Paul Bettany, David Thewlis and Chazz Palminteri.

Had the filmmakers gone for a full dark comedy vibe, this could have been a nasty little cult crime comedy. Unfortunately, Helgeland can’t seem to decide if he wants to make that movie or a ‘Goodfellas’-lite Krays retelling or a tragic romance. Ultimately, the movie awkwardly sputters between those three tones, but thankfully Hardy grounds it with two of the most entertaining performances you’ll see all year. Seek out ‘Legend’ for him alone. Everything else is necessary containment unit for his performances.